Background and purpose: The objective of this study was to analyze the trunk muscle activation patterns, spine kinematics, and lumbar compressive forces that occur when using the Bodyblade, a popular tool in physical medicine clinics.
Subjects: The participants were 14 male subjects who were healthy and who were recruited from a university population.
Methods: With data collected from surface electromyography of selected trunk and shoulder muscles, video analysis, and a 3-dimensional lumbar spine position sensor, modeling methods were used to quantify L4-5 compressive forces and spine stability.
Results: Large-amplitude oscillation of a vertically oriented Bodyblade resulted in the greatest activation levels of the internal oblique and external oblique muscles (average amplitude=48% and 26% of maximal voluntary isometric contraction, respectively), which were associated with L4-5 compressive forces as high as 4,328 N. Instantaneous stability increased with well-coordinated effort, muscle activation, and compression, but decreased when subjects had poor technique.
Discussion and conclusion: The way the Bodyblade is used may either enhance or compromise spine stability. Associated lumbar compressive forces may be inappropriate for some people with compression-intolerant lumbar spine pathology.